Tens of thousands of other caregivers in the disability and homecare sectors, supermarket checkout operators and other retail staff, teacher-aides and other school support workers, hotel housekeepers, restaurant staff, bank tellers, librarians and social workers could all potentially use the case as a precedent for court actions.
A similar case in Australia in 2012 ordered 4000 mainly non-profit agencies to raise the wages of 150,000 mainly female disability and homecare workers by between 19 and 41 per cent over eight years.
Aged Care Association chief executive Martin Taylor says the Bartlett case could cost $120 million to $140 million a year for the 33,000 workers in residential aged care alone.
"Then you have the homecare people and the disability people, so you have years and years of people taking equal pay claims through the Employment Court," he warns.
He believes the Government will be forced to legislate to confine the contagion if the Supreme Court upholds the proposed legal principle.
But Business NZ chief Phil O'Reilly is more cautious.
"Potentially, worst-case scenario, it could have very significant cost implications on the economy," he says.
"But it might also have no implications at all if the Supreme Court turns it down and says away you go, or if the Government does act. It certainly has some pretty serious consequences, but I think my sense is we need to take a deep breath and let the process run its course."
The pay gap
Before 1972, male wages were fixed through a court-backed system "to enable a male breadwinner to support a wife and three children". Female rates were usually lower; for example, the minimum wage for women in 1949 was 70 per cent of the male minimum.
The Equal Pay Act made it illegal to set different rates by gender, raising the actual average female hourly wage from 69.9 per cent of the male average in 1972 to 78.5 per cent by the end of a phase-in period in 1978.
But since then there has been only slow progress towards closing the remaining gap, and by September this year women still averaged only 87.1 per cent of men's wages - $26.49 an hour against $30.43 for men.
Labour Department economist Sylvia Dixon found in 2000 that the biggest observable factor holding down women's wages at that time was that they had less paid work experience because they had spent time caring for children. On average, women aged 20 to 59 had been in paid work for only 11.2 years compared with 18.4 years for men. At that time men were also better educated.
Both these factors have changed radically, probably explaining most of the narrowing of the pay gap since 1978. In the 1976 census only 40 per cent of women aged 20 to 64 were in or seeking paid work, compared with 94 per cent of men. By last year the figures were much more even: 73 per cent of women and 86 per cent of men.
In 1976, 64 per cent of new bachelor's degree graduates were men. By last year, 64 per cent were women.
Yet still men earn more than women on average in 14 out of 16 sectors (see graphic). A 2011 study by Education Ministry analyst Paul Mahoney found that women who finished bachelor's degrees in 2003 and stayed in paid work for the next four years earned the same incomes as equivalent male graduates in their first year of work, but after four years fell 9 per cent behind, averaging only $43,380 a year against $47,760 for the men.
The Campaign for Equal Value Equal Pay (CEVEP) believes this reflects often-unconscious discrimination both by individual employers, who may promote men faster than women, and by society, which still puts a lower value on "women's work" such as caring and cleaning than on "men's work" such as technology and trades.
The Bartlett case
Bartlett's union, the Service and Food Workers Union, says 92 per cent of New Zealand rest-home caregivers, including 111 of TerraNova's 117 caregivers, are female. Although TerraNova's six male caregivers were paid the same as the women, the union argued that all the caregivers' wages were lower than would be paid to men with similar skills, responsibility, experience and effort in an industry that was not female-dominated.
"The males are paid the same rate as the females because effectively they are 'honorary women'," says union secretary John Ryall.
TerraNova and the Aged Care Association replied that trying to compare caregivers with unrelated sectors would be unaffordable, unworkable, and would overturn a 1986 Arbitration Court judgment that inter-sector comparisons could be made only during the Equal Pay Act's phase-in period up to 1977.
That judgment led the Labour Government of the time to legislate in 1990 to allow inter-sector comparisons, but that law was repealed by an incoming National Government the next year.
However in the Bartlett case full benches of first three Employment Court judges, and then three Appeal Court judges, agreed unanimously that, where work is "exclusively or predominantly performed by female employees", the original 1972 law allows for a pay rate comparison in other industries.
The Appeal Court said the 1986 judgment was "not closely reasoned". As for the argument that rest homes and their Government funder could not afford the potential cost, Employment Court Chief Judge Graeme Colgan is reported to have said: "Cost arguments were made against the abolition of slavery."
The courts have not yet actually compared caregivers with any particular occupation. Instead, the Appeal Court suggests that the Employment Court should draw up more detailed principles which may "identify appropriate comparators and guide the parties on how to adduce evidence of other comparator groups or issues".
Who's next?
The Public Service Association is already running a campaign to apply the Bartlett precedent to about 35,000 other caregivers, beyond rest homes, who support people in their homes or with disabilities or mental illness.
"We have done a job evaluation," says assistant secretary Kerry Davies. "We have done a business case for the Ministry of Health."
A job evaluation was also done in 2008 for 600 support workers employed by the Education Ministry to help children with language, behaviour and other problems.
That was the first evaluation under Helen Clark's Labour Government policy that the public sector should "lead by example" on pay equity, and found that the support workers' jobs were roughly equivalent to prison officers in skills, responsibilities, and emotional and physical demands. Yet the support workers' top hourly pay is now only $19.29 compared with $32.07 for a senior corrections officer.
The ministry has been gradually reducing the numbers of support workers, replacing them with teacher aides employed by schools. Ryall sees teacher aides themselves, along with school secretaries, as other mainly female groups that could make pay claims based on the Bartlett case.
Labour's pay and employment equity unit also started an evaluation comparing social workers with meteorologists, but it was not finished before John Key's Government disbanded the unit in 2009.
Economist Prue Hyman says another public sector case could be made for librarians, "who compare themselves with geologists".
Sociologist Linda Hill says 10 claims were lodged under the short-lived 1990 pay equity law including general practice nurses compared with police, nurse aides compared with ambulance drivers, medical receptionists compared with hospital electrical workers, and cosmetics saleswomen compared with car-part salesmen. None were resolved before the law was repealed.
After health and social assistance, which employed 180,600 women in September, the next-biggest female employer is retailing, with 112,900 women making up 58.5 per cent of shopworkers. First Union retailing and finance secretary Maxine Gay says shop assistants and bank tellers are "a fairly obvious next group" for pay equity claims.
Hotel and restaurant staff are also heavily female (59.9 per cent) and are our lowest-paid workers, averaging just $18.93 an hour for men and $17.16 for women. Unite Union director Mike Treen sees a possible pay equity claim for the 2000 housekeepers in tourist hotels who work on or near the minimum wage of $14.25 an hour.
Challenges to come
However, all these claims will face several major challenges even if Kristine Bartlett's claim ultimately succeeds.
First, the court-based pay-fixing system of 1972 disappeared with the 1991 Employment Contracts Act. Most employees now work on individual contracts so may not know how their pay compares to the person working next to them, let alone in another industry. Averages such as those used in this article may vary for many reasons besides gender discrimination.
Second, many female sectors such as hairdressers and clerical workers have become deunionised since 1991 so they have no one to fight a claim.
Third, as women have become more educated than men and less likely to take much time off work for children, occupations have become more mixed. An Institute of Economic Research study found that managers, professionals, sales and service workers all became less "gender-segregated" between 1981 and 2006, although trades and other blue-collar workers stayed male.
And fourth, even where gender dominance remains, male groups are no longer always better paid. Instead, increasing inequality generally means higher margins for skills, and men's lower education levels are pushing some down the pay scale.
Looking for groups to compare with shop and bank workers, Gay comments: "Some of the obvious comparators are low-paid as well, security guards for example."
"Shop work throughout the world is under-valued. Is that a gender undervaluing or not?" she asks. "My instincts tell me that it is, but we would have to do a lot more work [to prove it]."
Wages fall short despite huge contribution to the future of our children
Speech Communication support worker Denise Tetzlaff with five year old Tafi Fa'amoe from Avondale Primary. Photo/ Greg Bowker
Denise Tetzlaff is responsible for 11 children with speech and language difficulties, yet after 16 years in the job she still earns only $19 an hour.
"My job is to work with children aged 5 to 8 who have difficulties with pronouncing consonants, have very little language, or language delay for one reason or another," she says.
"It could be medical, it could be just the way they have lived their lives up to the age of 5."
She has three 45-minute sessions a week with each child, driving between 10 schools stretching from Avondale to Mangere.
Normally two sessions a week are one-on-one and in the third session she supports the child in their class.
"I call myself a speech and language therapist's assistant," she says.
She is employed by the Ministry of Education and works under a trained therapist who also visits each child once a fortnight.
Tetzlaff, 55, trained on the job. "I previously was a typist with shorthand-typing, and I was a teacher aide when my children were little," she says.
"Normally they try to give us some training once a term, learning about Asperger's, autistic children, speech and language needs."
She usually stays with each child for two terms and sees most of them make a lot of progress, "depending on the severity of their needs".
But for the past two and a half years she has earned only $19 an hour, the top rate for her group, which includes behaviour support workers in primary schools and education support workers in pre-schools as well as her own specialty, communication support workers.
She has been part of an NZ Educational Institute team that has just negotiated a pay rise of 1.5 per cent now, taking pay rates to $16.28 at the bottom and $19.29 at the top, plus another 1 per cent next year.
"I'm not doing this job for the money," she says. She and her husband have two adult children and are still paying off a mortgage.
"I've been in this role for so long because, in my opinion, I'm contributing to the future of this country."
"The child that I work with now could be the next Prime Minister, could be the mayor of Auckland City, you don't know. I enjoy working with the children."
Job danger worth more
Beven Hanlon earned $66,711 as a senior corrections officer and reckons he was underpaid.
He was a prison officer for 17 years until he became full-time president of the Corrections Association, representing 2753 of the country's 3500 prison staff.
His final salary works out at $32.07 an hour, not much above the average wage of $28.62. He thinks senior prison officers are worth more than that because of the dangers they face.
"There are 20 to 30 serious assaults on officers in a year that require being in hospital for more than two days."
New prison officers don't have to have external qualifications, but there is an internal 12-week training course. They get pay increases to do further training to levels 3 and 4 on the qualifications framework.
"Sixty to 70 per cent are on level 4," Hanlon says.
He says people like Denise Tetzlaff deserve better pay for working with children with learning and behaviour difficulties.
"If they get it wrong, we end up with them, eh?" he says. "And it costs the taxpayer a heap more if we're looking after them."
On the web: cevepnz.org.nz
